The present invention relates to a system for permitting rapid removal and reinsertion of angioplasty catheters, and is particularly useful in connection with fixed wire coronary balloon angioplasty catheters.
Percutaneous transluminal coronary angioplasty (PTCA) has gained widespread acceptance as a significantly less-invasive alternative to coronary bypass surgery. A similar technique, peripheral angioplasty, is useful in treatment of peripheral vascular disease. Unlike bypass surgery, PTCA does not require general anesthesia, cutting of the chest wall, extracorporeal profusion, or transfusion of blood.
During PTCA and other balloon angioplasty procedures, a catheter bearing an angioplasty balloon at the distal end is threaded into a stenosis (restriction of the artery) under fluoroscopic observation. Contrast agent is injected during the positioning process in order to permit real time imaging of the vasculature into which the catheter is inserted.
Once the catheter is in place in the stenosis, the angioplasty balloon is inflated, dilating the stenosis.
It is important that the inflated diameter of the balloon be matched to the native diameter of the stenotic vessel. A balloon that is too small will produce suboptimal dilation, while a balloon that is too large could result in arterial wall damage. Physicians tend to err on the side of choosing smaller (rather than larger) angioplasty balloons.
There are numerous occasions in which removal of the angioplasty catheter and reinsertion of another catheter may be required during PTCA. For example, coronary occlusion may occur during angioplasty. Dilation of one vessel may result in restriction of another, adjacent stenotic vessel. Furthermore, dissection of the arterial wall may occur during angioplasty. In both of these events, placement of a perfusion catheter through the stenotic region may be of utmost importance.
Furthermore, if the balloon chosen by the physician turns out to be a less than optimal size, removal of the angioplasty catheter and reinsertion of a different angioplasty catheter may be necessary.
One type of angioplasty catheter in widespread use is the over the wire catheter. This catheter has a guidewire lumen through which a steerable guidewire may be advanced. The guidewire (which extends distally beyond the distal end of the angioplasty catheter) is typically first positioned in the stenosis. Next, the catheter is advanced over the guidewire into the stenosis. If catheter exchange is necessary, the catheter may be removed from the patient leaving the guidewire in place, and a new catheter may be rapidly advanced over the positioned guidewire into the stenosis.
Another type of angioplasty catheter in widespread use is the fixed wire catheter. In this catheter, the distal end of the angioplasty balloon is actually bonded to the guidewire. Thus, the guidewire is "fixed" with respect to the location of the balloon. A major advantage of the fixed wire catheter is the elimination of the guidewire lumen extending through the balloon, permitting the deflated fixed wire balloons to have an extremely low profile. However, a significant disadvantage of the fixed wire catheter is the inability to rapidly remove the catheter and reinsert a different catheter into the same vasculature location. When the fixed wire catheter is removed, the guidewire is removed at the same time. Insertion of a new catheter is somewhat time consuming, requiring additional injection of contrast material and fluoroscopic observation during positioning of the second catheter. In essence, replacing a catheter with a second fixed-wire catheter is like starting the procedure all over again.
Accordingly, there is a substantial need for a system for bailing out fixed wire angioplasty catheters; that is, a system for permitting the removal of the fixed wire catheter and rapid and assured reinsertion of a second catheter into the same vascular location. Similarly, there is a need for a method for accomplishing that result.